Patients with Covid 19 have significantly reduced CH50 activity

Relevance of complement immunity with brain fog in patients with long COVID

INTRODUCTION

This study aimed to elucidate the prevalence and clinical characteristics of patients with long COVID (coronavirus disease 2019), especially focusing on 50% hemolytic complement activity (CH50).

METHODS

This retrospective observational study focused on patients who visited Okayama University Hospital (Japan) for the treatment of long COVID between February 2021 and March 2023. CH50 levels were measured using liposome immunometric assay (Autokit CH50 Assay, FUJIFILM Wako Pure Chemical Corporation, Japan); high CH50 was defined as ≥59 U/mL. Univariate analyses assessed differences in the clinical background, long COVID symptoms, inflammatory markers, and clinical scores of patients with normal and high CH50. Logistic regression model investigated the association between high CH50 levels and these factors.

RESULTS

Of 659 patients who visited our hospital, 478 patients were included. Of these, 284 (59.4%) patients had high CH50 levels. Poor concentration was significantly more frequent in the high CH50 group (7.2% vs. 13.7%), whereas no differences were observed in other subjective symptoms (fatigue, headache, insomnia, dyspnea, tiredness, and brain fog). Multivariate analysis was performed on factors that could be associated with poor concentration, suggesting a significant relationship to high CH50 levels (adjusted odds ratio [aOR], 2.70; 95% confidence interval [CI], 1.33-5.49). Also, high CH50 was significantly associated with brain fog (aOR, 1.66; 95% CI, 1.04-2.66).

CONCLUSIONS

High CH50 levels were frequently reported in individuals with long COVID, indicating a relationship with brain fog. Future in-depth research should examine the pathological role and causal link between complement immunity and the development of long COVID.

Systemic lupus erythematosus flare during SARS-CoV-2 infection: Report of 3 cases presented during the fourth wave of the pandemic in Colombia

BACKGROUND

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus has become a worldwide pandemic since first discovered in 2019. Systemic lupus erythematosus (SLE) flare has been reported in the post-infectious period. In Colombia, the fourth pandemic wave started at the beginning of 2022 when we observed flare of 3 SLE patients during active infection.

CASE PRESENTATION

We describe 3 patients with inactive SLE, who presented coronavirus disease 2019 and severe flare in early 2022, 2 patients with nephritis and 1 with severe thrombocytopenia. All patients had increase of antinuclear and anti-DNA antibody titers and complement consumption.

CONCLUSIONS

Three cases with SLE flare concomitant with active SARS-CoV-2 infection were different from others reported earlier in the pandemic with post-infectious flare.

Complement and COVID-19: Three years on, what we know, what we don't know, and what we ought to know

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus was identified in China in 2019 as the causative agent of COVID-19, and quickly spread throughout the world, causing over 7 million deaths, of which 2 million occurred prior to the introduction of the first vaccine. In the following discussion, while recognising that complement is just one of many players in COVID-19, we focus on the relationship between complement and COVID-19 disease, with limited digression into directly-related areas such as the relationship between complement, kinin release, and coagulation. Prior to the 2019 COVID-19 outbreak, an important role for complement in coronavirus diseases had been established. Subsequently, multiple investigations of patients with COVID-19 confirmed that complement dysregulation is likely to be a major driver of disease pathology, in some, if not all, patients. These data fuelled evaluation of many complement-directed therapeutic agents in small patient cohorts, with claims of significant beneficial effect. As yet, these early results have not been reflected in larger clinical trials, posing questions such as who to treat, appropriate time to treat, duration of treatment, and optimal target for treatment. While significant control of the pandemic has been achieved through a global scientific and medical effort to comprehend the etiology of the disease, through extensive SARS-CoV-2 testing and quarantine measures, through vaccine development, and through improved therapy, possibly aided by attenuation of the dominant strains, it is not yet over. In this review, we summarise complement-relevant literature, emphasise its main conclusions, and formulate a hypothesis for complement involvement in COVID-19. Based on this we make suggestions as to how any future outbreak might be better managed in order to minimise impact on patients.

Associations between serum levels of C3, C4, and total classical complement activity in COVID-19 patients at the time of admission and clinical outcome

In the present study, we investigated the association between complement system status at the time of admission and clinical outcomes in COVID-19 patients. This single-center study was carried out with sixty-one adult patients with COVID-19 who were hospitalized at Imam Hassan Hospital of North Khorasan University of Medical Sciences (Bojnurd, Iran) with less than three days passage since onset of COVID-19 symptoms. Twenty-three healthy volunteers with demographic features similar to the patient group (matched by age and gender) were included in the study as a control group. Patient information including demographic information, demographic data, clinical characteristics, and clinical outcomes were obtained from electronic medical records. Of 61 hospitalized patients with COVID-19, 28 (47.54%) were female, and the average age was 48.78.8 years. The healthy control group included 23 cases (11 (47.8%) female, 12 (52.1%) males, mean age 46.44.4 years). Twenty-one of the 61 patients (34.4%) were admitted to the ICU, and sixteen of them (26.2%) died. Thirty-three (54.10%) patients with COVID-19 were hospitalized for less than 7 days, and 28 (45.90%) of them were hospitalized for 7 days. Our results show that length of hospital stay in the no-ICU group was significantly lower than the ICU admission or death groups (6.490.24 vs. 8.851.59 and 10.531.80, p = 0.0002). The levels of C3, C4, and CH50 were determined through the immunoturbidimetric method and single-radial-haemolysis plates, respectively, on serum samples obtained from patients at the time of admission or those in the control group. Our results indicate that C3, C4 and CH50 levels were markedly lower in COVID-19 patients than in the control group. We also found that complement parameter levels in COVID-19 patients who died or were admitted to ICU were significantly lower than in non-ICU COVID-19 patients. In general, it seems that serum level of C3, C4, and CH50 at admission may predict disease progression or adverse clinical outcome in COVID-19 patients.

Complement C1s as a diagnostic marker and therapeutic target: Progress and propective

The molecules of the complement system connect the effectors of innate and adaptive immunity and play critical roles in maintaining homeostasis. Among them, the C1 complex, composed of C1q, C1r, and C1s (C1qr₂s₂), is the initiator of the classical complement activation pathway. While deficiency of C1s is associated with early-onset systemic lupus erythematosus and increased susceptibility to bacteria infections, the gain-of- function variants of C1r and C1s may lead to periodontal Ehlers Danlos syndrome. As C1s is activated under various pathological conditions and associated with inflammation, autoimmunity, and cancer development, it is becoming an informative biomarker for the diagnosis and treatment of a variety of diseases. Thus, more sensitive and convenient methods for assessing the level as well as activity of C1s in clinic samples are highly desirable. Meanwhile, a number of small molecules, peptides, and monoclonal antibodies targeting C1s have been developed. Some of them are being evaluated in clinical trials and one of the antibodies has been approved by US FDA for the treatment of cold agglutinin disease, an autoimmune hemolytic anemia. In this review, we will summarize the biological properties of C1s, its association with development and diagnosis of diseases, and recent progress in developing drugs targeting C1s. These progress illustrate that the C1s molecule is an effective biomarker and promising drug target.

Complement-mediated microvascular injury and thrombosis in the pathogenesis of severe COVID-19: A review

Coronavirus disease 2019 (COVID-19) causes acute microvascular thrombosis in both venous and arterial structures which is highly associated with increased mortality. The mechanisms leading to thromboembolism are still under investigation. Current evidence suggests that excessive complement activation with severe amplification of the inflammatory response (cytokine storm) hastens disease progression and initiates complement-dependent cytotoxic tissue damage with resultant prothrombotic complications. The concept of thromboinflammation, involving overt inflammation and activation of the coagulation cascade causing thrombotic microangiopathy and end-organ damage, has emerged as one of the core components of COVID-19 pathogenesis. The complement system is a major mediator of the innate immune response and inflammation and thus an appealing treatment target. In this review, we discuss the role of complement in the development of thrombotic microangiopathy and summarize the current data on complement inhibitors as COVID-19 therapeutics.